Boxford A3 HSRi Axis overtravel and spindle overheating - help!

[JAZZCNC]

Tom sounds like you have a few issues going on here. I can help but it will mean you trying one thing at a time giving clear replys to my questions and not going off at tangents.

Has this machine ever worked correctly while in you owned it. Or have you bought it like this.?

Can you run the spindle without CNC side being turned ON so we can identify if the spindle is getting hot and transfering heat to machine.
I don't see any speed controller inside the Control box you showed so I'm presuming the spindle has manual speed control or fixed speed.! Which is it.?
OR is there another board or electronics your not showing.?

Need you to CUT air WITHOUT the spindle running and at the normal feedrate. But I want you to NOT turn on power to the machine until last minute. Then quickly load program and start cutting air.
Take a note of the Stepper temps and check at intervals while cutting air to see if they get hot. And how long before they do. It's not unusual for steppers to get hot while stood at rest so this is why I need you to start from cold and check temps.
While cutting they should be just above warm to mildly hot, and when at stand still for ten to fifteen minutes be like holding a cup of tea or coffee after minute or so off boil.!! . . They shouldn't burn.

Try this and let me know.!